Ion generator regulator



Jan- 31, 1955 R. DE LIBAN lION GENERATOR REGULATOR 5 Sheets-Sheet l Filed Sept. 18, 1945 v E INVENTOR. @05E/QT 0e mA/v ATTORNEY.

Jan. 31, 1956 R. DE LIBAN 2,733,344

10N GENERATOR REGULATOR Filed Sept. 18, 1945 5 Sheets-Sheet 2 ATTORNEY.

Jan. 3l, 1956 R. DE LIBAN ION GENERATOR REGULATOR 3 Sheets-Shea t 3 Filed Sept. 18. 1945 ACTUAL RANGE THEORET/CAL RA NGE 4 our ,4. C. SUPPLY A Z Q m AR D a mm D.CI ARC CURRENT /N AMPEREJ 0 O U w w MUNQO lL//VE VOL 75465 @56. MAX @A nso 20 rRAA/JFQRMER TYP/CAL CD/VTRL CURVE 7'W/N TIP/ODE GR/D VOLTAGE INVENTOR. ROBERT De L/BA/v /JAA/f M ATTORNEY.

United States Patent ION GENERATOR REGULATOR Robert De Liban, Berkeley, Calif., assignor to the United States of America as represented by the United States Atomic Energy Commission Application September 18, 1945, Serial No. 617,131

6 Claims. (Cl. Z50-41.9)

The present invention relates to regulators for electric discharge devices and more particularly to regulators for calutron ion sources.

It is an object of this invention to provide an improved regulator for stabilizing the operation of a calutron ion generator.

Another object of this invention is to provide an improved regulator for stabilizing the operation of a calutron ion generator of the arc discharge type employing a lamentary cathode.

Still another object of this invention is to provide an improved regulator for a calutron ion generator of the type employing a iilamentary cathode energized by alternating current.

At the outset, it is noted that a calutron is a machine of the character of that disclosed in the copending application of Ernest O. Lawrence, Serial No. 557,784, led October 9, 1944, now Patent No. 2,709,222, and is employed to separate the constituent isotopes of an element and, more particularly, to increase the proportion of a selected isotope in an element containing several isotopes in order to produce the element enriched with the selected isotope. For example, the machine is especially useful in producing uranium enriched with U235.

Such a calutron essentially comprises means for vaporizing a quantity of material containing an element that is to be enriched with a selected one of its several isotopes; means for subjecting the vapor to ionization, whereby at least a portion of the vapor is ionized causing ions of the several isotopes of the element to be produced; electrical means for segregating the ions fromvthe 11n-ionized vapor and for accelerating the segregated ions to relatively high velocities; electromagnetic means for deiecting the ions along curved paths, the radii of curvature of the paths of the ions being proportional to the square roots of the masses of the ions, whereby the ions are concentrated in accordance with their masses; and means for de-ionizing and collecting the ions of the selected isotope thus concentrated, thereby to produce a deposit of the element enriched with the selected isotope.

The invention, both as to its organization and method of operation together with other objects and advantages thereof, will best be understood by reference to the following specication taken in connection with the accompanying drawings in which Fig. l is a diagrammatic plan view of a calutron and associated supply circuit together with the improved ion generator regulator;

Fig. 2 is a diagrammatic sectional View of the calutron taken along the line 2 2 of Fig. l;

Fig. 3 is a schematic wiring diagram of the ion generator regulator shown in block form in Fig. 1;

Fig. 4 is a schematic wiring diagram employed for purposes of facilitating the explanation of the operation of Fig. 3;

Fig. 5 is a diagram showing the phase relations of certain voltages across elements of the circuit diagram shown in Fig. 4; Y

Fig. 6 is a curve showing the relation between the arc race current of the ion generatorand the rectified signal voltage; and

Fig. 7 is a curve showing the relation between the ion generator regulator grid voltage and the primary voltage of the ion generator filament.

Referring now more particularly to Figs. l and 2 of the drawings, there is illustrated a representative example of a calutron 10 of the character noted, that comprises magnetic field structure including upper and lower pole pieces 11 and 12, provided with substantially iiat parallel spaced-apart pole faces, and a tank 13 disposed between the pole faces of the pole pieces 11 and 12. The. pole pieces 11 and 12 carry windings, not shown, which are adapted to be energized in order to produce a substantially uniform and relatively strong magnetic field therebetween, which magnetic eld passes through the tank 13 and the various parts housed therein. The tank 13 is of tubular configuration, being substantially crescent-shaped in plan, and comprising substantially flat parallel spacedapart top and bottom walls 14 and 15, upstanding curved inner and outer side Walls 16 and 17, and end walls 13 and 19. VThe end Walls 18 and 19 close the opposite ends of the tubular tank 13 and are adapted to be removably secured in place, whereby the tank 13 is hermetically sealed. Also, vacuum pumping apparatus, not shown, is associated with the tank 13, whereby the interior of the tank 13 may be evacuated to a pressure of the order of l0-5 to 10-4 mm. Hg. Preferably, the component parts of the tank 13 are formed of steel, the top and bottom walls 14 and 15 thereof being spaced a short distance from the pole faces of the upper and lower pole pieces 11 and 12, respectively, the tank 13 being retained in such position in any suitable manner, whereby the top and bottom walls 14 and 1S constitute in eifect pole pieces with respect to the interior of the tank 13, as explained more fully hereinafter.

The removable end wall 18 suitably supports a source unit 2t) comprising a charge receptacle 21 and a communieating arc block 22. An electric heater 54 is arranged in heat exchange relation with the charge receptacle 21 and is adapted to be connected to a suitable source of heater supply, whereby the charge receptacle 21 may be appropriately heated, the charge receptacle 21 being formed of steel or the like. The arc block 22 is formed, at least partially, of carbon or graphite and is substantially C-shaped in plan, an upstanding slot 24 being formed in the wall thereof remote from the charge receptacle 21. Thus, the arc block 22 is of hollow construction, the cavity therein communicating with the interior of the charge receptacle 21.

Also, the removable end wall 18 carries a lamentary cathode 25 adapted to be connected to a suitable source of lament supply 52, the iilamentary cathode 25 overhanging the upper end of the arc block 22 and arranged in alignment with respect to the upper end of the cavity formed therein. The arc block 22 carries an anode 26 disposed adjacent the lower end thereof and arranged in alignment with respect to the cavity formed therein. The lilamentary cathode 25 and the cooperating anode 26 are adapted to be connected to a suitable source of voltage and current hereinafter referred to as arc voltage supply 55.

Further, the removable end wall 18 carries ion accelerating structure 39 formed of carbon or graphite and disposed in spaced-apart relation with respect to the Wall of the Varc block 22 in which the slot 24 is formed. More speciically, a slit 40 is formed in the ion accelerating structure 39 and arranged in substantial alignment with respect to the slot 24 formed in the wall of the arc block 22. A suitable source of accelerating electrode supply 57 is adapted to be connected with its positive terminal to the calutron ground and with its negative terminal to the ion accelerating structure 39. A suitable source of decelerat- 3 ing potential 56 is adapted to be connected with its positive terminal to the positive terminal of the arc voltage supply and its negative terminal grounded.

The removable end wall 19 suitably supports a collector block 29 formed of stainless steel or the like and provided with two laterally spaced-apart cavities or pockets 3G and 31 which respectively communicate with aligned slots 32 and 33 formed in the wall of the collector block 29 disposed remote from the removable end wall 19. lt is noted that the pockets 3i) and 31 are adapted to receive two constituent isotopes of an element which have been separated in the calutron 10, as explained more fully hereinafter. Further, the inner wall 16 suitably supports a tubular liner 34 formed of copper or the like, rectangular in vertical cross-section, disposed within the tank 13 and spaced from the walls 14, 1S, 16 and 17. One end of the tubular liner 34 ternlinates adjacent the accelerating structure 39; and the other end of the tubular liner 34- terminates adjacent the collector block 29; the tubular liner 34 constituting an electrostatic shield for the high velocity ions traversing the curved paths between the slit 40 formed in the ion accelerating structure 39 and the slots 32 and 33 formed in the collector block 29. Finally, the tubular liner 34 is electrically grounded to the calutron ground. Thus, it will be understood that the source unit is connected to the positive terminals or the arc voltage supply 55 and the decelerating potential supply S6 and the tank 13 and liner 34 are connected to the positive grounded terminal of the accelerating electrode supply and the negative grounded terminal of the decelerating supply; while the ion accelerating structure 39 is connected to the ungrounded negative terminal of the accelerating electrode supply 57'; the ion accelerating structure 39 and the collector block 29 being electrically insulated from the component parts of the tank 13.

Considering now the general principle of operation of the calutron 1t?, a charge comprising a compound of the element to be treated is placed in the charge receptacle 21, the compound of the element mentioned being one which may be readily vaporized. The end walls 18 and 19 are securely attached to the open ends of the tank 13, whereby the tank 13 is hermetically sealed. The various electrical connections are completed and operation of the vacuum pumping apparatus, not shown, associated with the tank 13 is initiated. When a pressure of the order of 105 to 1O-l mm. Hg is established within the tank 13, the electric circuits for the windings, not shown, associated with the pole pieces 11 and 12 are closed and adjusted, w ereby a predetermined magnetic lield is established therebetween traversing the tank 13. The electric circuits between the arc block heater 53 and supply 50 and the charge receptacle heater 54 and supply 51 are closed, whereby the charge in the charge receptacle 21 is heated and vaporized and arc block brought up to operating temperature. The vapor lls the charge receptacle 21 and is conducted into the communicating cavity formed in the are block 22. The electric circuit for the tilamentary cathode is closed, whereby the lilamentary cathode is heated and rendered electron emissive. Then the electric circuit between the larnentary cathode 25 and the anode 26 is closed, whereby an arc discharge is struck therebetween, electrons proceeding from the fllamentary cathode 25 to the anode 26. The stream of electrons proceeds into the arc block 22 and breaks up the molecular form of the compound of the Vapor to a considerable extent, producing positive ions of the element that is to be enriched with the selected one of its isotopes.

The electric circuit between the arc block 22 and the ion accelerating structure 39 is completed, the ion accelerating structure 39 being at a high negative potential with respect to the are block 22, whereby the positive ions in the arc block 22 are attracted by the ion accelerating structure 39 and accelerated through the voltage impressed therebetween. More particularly, the positive ions proceed from the cavity formed in the are block 22 through the slot 24 formed in the wall thereof, and across the space between the ion accelerating structure 39 and the adjacent wall of the arc block 22, and thence through the slit 40 formed in the ion accelerating structure 39 into the interior of the tubular liner 34. However, in passing into the liner 34 the positive ions suffer a slight deceleration since the liner 34 is at a positive potential with respect to the accelerator 39. The high-velocity positive ions form a vertical upstanding ribbon or beam proceeding from the cavity formed in the are block 22 through the slot and the aligned slit 40 into the tubular liner 3d.

As previously noted, the collector block 29 and the tubular liner 34 are electrically connected and grounded whereby there is an electric-iield-free path for the highvelocity positive ions disposed between the ion accelerating structure 39 and the collector block 29 within the tubular liner 34. The high-velocity positive ions entering the adjacent end of the liner 34 are dellected from their normal straight-line path and from a vertical plane passing through the slot 24 and the aligned slit 40, due to the effect of the relatively strong magnetic lield maintained through the space within the tank 13 and the liner 34 through which the positive ions travel, whereby the positive ions describe arcs, the radii of which are proportional to the square roots of the masses of the ions and consequently of the isotopes of the element mentioned. Thus, ions of the relatively light isotope of the element describe an interior arc of relatively short radius and are focused through the slot 32 into the pocket 3i) formed in the collector block 29; whereas ions of the relatively heavy isotope of the element describe an eX- terior arc of relatively long radius and are focused through the slot 33 into the pocket 31 formed in the collector block 29. Accordingly, the relatively light ions are collected in the pocket Sil and are de-ionized to produce a deposit of the relatively light isotope of the element therein; while the relatively heavy ions are collected in the pocket 31 and are de-ionized to produce a deposit of the relatively heavy isotope of the element therein.

After all of the charge in the charge receptacle 21 has been Vaporized, all of the electric circuits are interrupted and the end wall 18 is removed so that another charge may be placed in the charge receptacle 21 and subsequently vaporized iny the manner explained above. After a suitable number of charges have been vaporized in order to obtain appropriate deposits of the isotopes of the element in the pockets 3() and 31 of the collector block 29, the end wall 19 may be removed and the deposits of the collected isotopes in the pockets 30 and 31 in the collector block 29 may be reclaimed.

Of course, it will be understood that the various dimensions of the parts of the calutron 10, the various electrical potentials applied between the various electrical parts thereof, as well as the strength ol the magnetic eld between the pole pieces 11 and 12, are suitably correlated with respect to each other, depending upon the mass numbers of the several isotopes of the element which is to be treated therein. In this connection reference is again made to the copending application of Ernest O. Lawrence, for a complete specification of a calutron especially designed for the production of uranium enriched with the isotope U235. By way of illustration, it is noted that when the calutron 10 is employed in order to produce uranium enriched with U235, the compound of uranium which is suggested as a suitable charge in the charge receptacle 21 is UCl4, as this compound may be readily vaporized and the molecular form of the vapor may be readily broken up to form positive ions of uranium with great facility. In this case, uranium enriched with U235 is collected in the pocket 30 of the collector block 29, and uranium comprising principally U23S is collected in the pocket 31 of the collector block 29. Also, it is noted that from a practical standpoint, the deposit of uranium collected in the pocket 30 of the collector block 29 contains considerable amounts of 'U238, in view of the fact that this isotope comprises the dominant -constituent of normal uranium. Furthermore, the deposit of uranium collected in the pocket 30 of the collector block 29 contains a considerably increased amount of U234, in view of the fact that it is not ordinarily feasible to separate U234 and U235 in the production of relatively large quantities of uranium enriched with U235 for commercial purposes. Accordingly, in this example the uranium deposited in the pocket 30 of the collector block 29 is considerably enriched, both with U234 and with U235, and considerably impoverished v-with respect to U238 as compared to natural or normal uranium.

In the operation of the calutron 10, it is highly desirable that a relatively intense stable beam of positive ions be projected by the ion accelerating structure 39, through the liner 34, toward the collector block 29; which operating condition requires that the source unit 20 be productive of a steady and copious supply of positive ions. To accomplish this end in the source unit 20, the arc discharge through the cavity in the arc block 22 must be both relatively intense and uniform. Moreover, it is desirable that such an arc discharge should be steady and free from both intensity and position variations in order that the ion source unit 20 be productive of a highly continuous, copious and uniform supply of positive ions. Furthermore, the ion source unit 20 should be so constructed and arranged that the parts thereof are subjected to minimum wear and erosion, whereby the unit has a long life and an efficient operating characteristic.

Having described the structural features of the calutron and the general operation thereof, the electrical circuit connections between the various electrodes and elements of the ion generator and regulator and the various sources of supply will now be described. Sources of current supply 50, 51 and 52 which` are energized from different phasesof the same polyphase power circuit are connected tothe arc block heater 53 to the charge receptacle heater S4 and the ion generator filament 25, respectively, as was hereinbefore briefly pointed out.. One side of the filament 25 is also connected to the negative terminal of the arc voltage supply 55 and the positive terminal of this arc voltage supply is connected to the positive terminal of the decelerator voltage supply 56 and to the anode 26 of the ion generator 20 as well as to the arc block 22 thereof. The negative terminal of the decelerator voltage supply is grounded as is the liner 34 of the calutron. The positive terminal of the accelerator voltage supply S7 is also grounded and the negative terminal of this supply is `connected to the accelerator structure 39 which is positioned between the ion generator 2t) and the liner 34 in such manner that the slots thereof are substantially in alignment. Terminals I, E, M of the regulator 58, which controls the heating current to the ion generator filament 25 in accordance with the arc current, are connected to be supplied with signal currents from three current transformers 59, 66 and 61 associated with the input power feeders of the arc voltage supply 55 so that this regulator may function to regulate through terminals XB the current fed to the filament power supply 52.V The terminals OR of the regulator 58 are connected across a phase of the supply voltage feeding the arc supply 55 for the purpose of closing the relay S4 when input voltage is connected to the arc supply 5S as will be hereinaftermore fully described. The secondaries of the current transformers 59, 60 and 61 are each shunted by resistors 63, 64 and 65, respectively, for the purpose of providing a permanent load on the secondaries.

The circuit arrangement of the regulator 58 is schematically set forth in Fig. 3 and reference is now made to this figure in detail.

The terminals I, E, M of the regulator apparatus are connected to the secondaries of the current transformers 59, 60 and 61, respectively, as pointed out', for supplying current to the transformers 67, 68 and 69. One terminal of each of the secondaries of the transformers 67, 68 and 69 is connected to an anode of each of the full-wave rectifiers 70, 71 and 72, respectively, and the other terminals of these secondaries are connected together. The other anodes of the full-wave rectifiers 7), 71 and 72 are connected together to the negative terminal of the variable resistor 73 through the condenser tuned choke coil 74. The appropriate cathodes and anodes of each of the rectifiers 70, 71 and 72 are connected together so -that these rectifier tubes form a full-wave three-phase rectifier. The cathodes which are connected together in these rectiers form the positive output terminal thereof and are connected to the positive terminal of the variable resistor 73 and, furthermore, a condenser 75 is connected across this variable resistor for filtering purposes. The variable contactor of this variable resistor is connected through a resistor 76 to both of the grid electrodes of the twin triode 77. The cathodes of this twin triode are also connected together and to the negative terminal of the rectifier bridge circuit 78, which terminal is also connected to one end of the resistor 79 and the other end of this resistor is connected to the positive terminal of the rectifier bridge 78. A variable contactor is provided to the resistor 79 and this is connected to the positive terminal of the resistor 73. A filter condenser 66 is connected across the resistor 79. The anodes of the twin triode are separately connected to the cathodes of a diode rectifier d() and the anodes of this diode are connected together to a terminal of the variable resistor 81. The other terminal of this variable resistor 31 is connected to a terminal of the variable resistor 82 and the other terminal of this latter resistor is connected to the negative terminal of the rectifier bridge 78 and the cathodes of the twin triodes 77. The terminals of the Variable resistor 82 are also connected to contactors 83 of the relay 84 and the winding of this relay is connected to the terminals OR which are connected to a phase of the arc supply input voltage as shown in Fig. l. The filaments of the rectifiers 79, 71, 72 and 80, the filament of the twin triode 77 and the A. C. terminals of the rectifier bridge 78 are all connected in parallel to the filament winding SS of the transformer 86. The anodes of the twin triode 77, in addition to being connected to the cathodes of the diode rectier Sti, are connected to the terminals of the condenser-resistor network 87 which includes the series-connected resistors 83 and 89 connected in series with the condenser 9i). One terminal of this condenser-resistor network is connected to a terminal of the secondary winding 91 of the transformer 86 and the other terminal of this secondary winding 91 is connected through resistor 92 to the resistor 89 and the condenser 9i). Condenser 93 is shunted across the resistor 92. The primaries of a pair of transformers 94 and 95 are connected in parallel to the condenser-resistor network 37 and the secondaries of these transformers 94 and 95 are connected to the inverseparallel thyratrons 96 and 97. It will be observed that the anode of the tube is connected to a terminal of the secondary of the transformer 95, to the cathode of the tube 97 and to the output terminal B. On the other hand, the anode of the tube 97 is connected to a terminal of the secondary of the transformer 94, to the cathode of the tube 96 and to the output terminal X through the resistor 98. .The other terminal of the secondary of the transformer 94 is connected through a condenser-resistor network 99 to the control grid of the thyratron 96 and the other terminal ofthe secondary of the transformer is connected through a condenser-resistor network to the control grid of the thyratron 97. The filaments of the thyratrons 96 and 97 are supplied heating currents from separate secondaries 101 and 102, respectively, of the transformer 86. 1

Thephysical connections of the apparatus shown in Fig. 3 and in block diagram in Fig. l having been described in detail, the operation thereof will now be considered.

From the foregoing description of the connections of the regulator apparatus 58 it will be seen that the terminals XB of the apparatus 58 are connected in series with the power supply 52 of the filament 25 of the ion source 20 so that current passing to the power supply 52 from the power feeders must pass through the thyratrons 96 and 97 of the regulator apparatus 58. The firing of these thyratrons 96 and 97 is controlled from a suitable phasing circuit in the apparatus 58. The signal for controlling the regulator apparatus 58 is obtained from the current transformers 59, 60 and 61 associated with the input circuit of the arc current supply 55 and the secondaries of these current transformers are connected to the terminals I, E, M of the apparatus 58. The signal obtained from the three-phase power circuit through the current transformers 59, 60 and 61 is applied to small step-up transformers 67, 68 and 69 connected in delta-Y to step up the signal voltage from the current transformers. The stepped up voltage is rectified by a conventional three-phase full-wave rectifier circuit employing the rectifiers 7 0, 71 and '72 and the output of this rectifieris filtered by means of a filter tuned to 360 cycles which reduces the time delay introduced into this regulator loop. The variable resistor 73 which is the arc current control, receives a portion of the rectifier output and this is compared with a standard voltage produced by the selenium rectifier bridge 78 which is fed from a regulated supply line and the resultant difference in voltages is applied to the grids of the twin triode 77 in the phasing section of the regulator apparatus. The tubes 77 and 80 of the phasing circuit function as A. C. resistance devices that can be varied over a wide range by a small change in D. C. grid potential applied to the twin triode 77. They thus furnish the required amplification and in addition, convert the varying D. C. signal corresponding to the difference between the standard voltage from the rectifier 78 and the rectifier output derived from the variable resistor 73, to an A. C. signal of varying phase. In practice, the equivalent resistance obtained in these tubes is not strictly linear and consequently introduces some symmetrical wave form distortion f the A. C. signal derived therefrom; however, this does not affect the operation of this apparatus. Since the input voltage supplied by the secondary 91 of the transformer 86 is small the D. C. grid voltage swing required on the grids of the twin triode 77 for a given phase shift is likewise small and, therefore, relatively high gain is obtained. However, too small a voltage supplied by winding 91 is undesirable as this may cause unbalance and instability in the output of the regulator because of the increased effect of variations in the critical grid voltage curves of the thyratrons 96 and 97.

Reference will now be made to Figs. 4 and 5 which are employed for the purpose of more clearly setting forth the operation of the phasing section of the regulator and this phasing section may be simplified to the elemental circuit shown in Fig. 4. rTheoretically, this elemental circuit is capable of shifting the phase of the output voltage through 180 while maintaining its amplitude constant, as the variable resistance ER is varied from zero to infinity. lu the regulator apparatus shown in Fig. 3 the voltage drop produced across the resistors 88 and 89 represents the input voltage EIN of Fig. 4, the condenser 93 corresponds to the capacitor EC of Fig. 4, the transformers 94 and 95 correspond to the load and the tubes 77 and 80 and resistors 81 and 82 correspond to the resistor ER. The voltage across the variable resistor ER is represented vectorially in Fig. together with the voltage EC across the condenser EC corresponding to the condenser 93 of Fig. 3, and the voltage EOUT which corresponds to the voltage applied to the primaries of the transformers 94 and 95. From reference to the vectors of Fig. 5 it is seen that as the value of the variable resis'tor ER is varied the phase of the voltage applied to the transformers 94 and 95 swings theoretically through an angle of 180; however, the actual range'of this swing is only about 140. This limited range is caused b'y'se'v# eral factors, namely, the imperfect regulation of the voltage supplied by the secondary 91, the loading effect of the transformers 94 and 95 and the effective resistance inserted by the tubes 77 and 80 cannot be reduced to zero. Furthermore, because of the latter reason the minimum phase lag is somewhat greater than zero and to compensate for this a prephasing system composed of the condenser 93 and the resistor 92 is employed for advancing the phase of the A. C. input voltage supplied by the secondary 91.

The thyratrons 96 and 97 have the grids thereof connected to the secondaries of the transformers 94 and 95, respectively, and these thyratrons are arranged so that a minimum over-all phase shift of zero is required for the firing thereof over a full half cycle, thereby supplying maximum voltage as permitted by the regulation of this apparatus, to the filament 25 of the ion generator of the calutron 10. The grid currents of the thyratrons 96 and 97 are limited by the grid resistors 99 and 100, respectively, and these grid resistors are shunted by capacitors which by-pass to ground through the condensers shunting the secondaries of the transformers 94 and 95, respectively, the sharp pulses produced during each halfcycle when the thyratron grids suddenly draw current. Furthermore, they also eliminate any effect the plate voltage wave may have on the firing point of the thyratrons due to the plate grid capacity coupling.

When the operation of the ion generator 20 is to be initiated current from the filament power supply 52 is supplied to the filament from one of the phases of a power circuit feeding the supply 52 through the terminals XB of the regulator 58. The current from the power supply feeders fed to the filament supply 52 passes through the thyratrons 96 and 97 of the regulator 58 and, of course, before the operating current for the filament 25 may pass through these thyratrons the cathodes thereof, connected to the filament windings 101 and 102 of the transformer 86 must be supplied with current and for this purpose the primary of the transformer 86 is connected to one of the phases of the polyphase circuit by conductors 103 and 104. When the filament 25 is first energized no arc current is supplied to the anode 26 and consequently signals are not supplied by the current transformers 59, 60 and 61 to the step-up transformers 67, 68 and 69, respectively, and the rectifiers 70, 71 and 72, respectively. Likewise, the contacts 83 of relay 84 are open at this time since no voltage is supplied to the winding of the relay. Therefore when the cathode 25 is first turned on both resistors 81 and 82 function to limit the minimum phase lag obtained in the phasing network since these resistors 81 and 82 are in effect connected in series with the twin triode 77 and diode rectifier 80 which form the automatically variable resistor elements of the phasing network. Thus when the cathode 25 is first turned on it is heated to approximately normal temperature. After the filament 25 of the ion generator 20 is raised to electron emissive temperature the arc current to the anode 26 of the ion generator 20 is turned on and signals are supplied to the regulator 58 by the current transformers 59, 60 and 61 and voltage is applied to the winding of the relay 84 which closes the contacts 83 whereby the resistor 82 is shorted. This leaves resistor 81 in circuit across the twin triode 77 and the diode 80 and since this resistor 81 is variable it may be used to limit theminimum phase lag obtainable and control the maximum ion generator filament current manually. The purpose of the relay 84 is to open the short across the resistor 82 when the voltage to the arc supply is interrupted and thus to automatically limit the current to the filament 25 by increasing the phase lag of the thyratron grid voltage.

After the arc voltage supply 55 connected to the anode 26 functions to supply arc voltage and current, signals determined by the magnitude of the arc current are supplied to the regulator 58, terminals I, E, M and the voltages of 'these signals are stepped up and applied to the rectiier's 70, 71 and 72. The output of these rectifiers is applied across the variable resistor 73 and the voltage across this variable resistor will therefore vary in accordance with the arc current supplied to the ion generator 20 as shown in Fig. 6. The variable resistor 73 may be designated as the arc current control since it picks off a portion of the rectified signals supplied thereto by the current transformers 59, 60 and 61 associated with the input of the arc current supply and this portion of the rectifier output is compared with a standard voltage produced by the selenium rectifier 78. The resultant dierence between these voltages is applied to the grids of the twin triode 77 and varies the resistance of this tube. As a result the phase shift of the voltage EOUT, as shown in vector diagram Fig. 5, is controlled by the grid voltage applied to the twin triode 77 and this, of course, is controlled by the arc current to the anode of the ion generator Z so that the magnitude of the arc current functions to control the firing of the thyratrons 96 and 97 since it controls the phase of the grid voltage applied to the grids of these tubes. The grid and plate voltages of the thyratrons must of course be in the proper phase relation. The thyratrons 96 and 97 in turn function to control the magnitude of the filament current supplied to the filament 25 of the ion generator 20. Thus the arc current of the ion generator is controlled by controlling the emission of the filament 25. When the arc current exceeds a certain predetermined value the filament emission from the filament 25 is decreased by decreasing the filament current so that the arc current is brought back to the predetermined value and the regulator apparatus in this way functions .in an effort to stabilize the arc current at the predetermined value. In a similar manner when the arc current is below the predetermined value the regulator functions to increase the filament current to increase the emission thereof and bring the arc current up. This predetermined value may be changed by manipulating the variable contactor of the variable resistor 73 which was referred to as thearc current control. As was pointed out previously, the material to be ionized is fed into the arc chamber between the filament 25 and the anode 26 and this material is subjected to the ionizing action of the arc which is regulated so that a uniform supply of ionized material is produced by the ion generator.

The signal for the regulator 58 may be obtained from the D. C. side of the arc supply 55 instead of the A. C. side as shown in Fig. 1 simply by connecting a high wattage fixed or variable resistor in series with either the positive or negative feeder of the D. C. arc supply, if the insulation is adequate, and the signal from this resistor may be fed to the Variable resistor 73 in place of the output from the rectiers 70, 71 and 72.

A current limiting resistor 98 is connected in series with the thyratrons 96 and 97 to limit the surge of current through the filament supply.

The curve shown in Fig. 6 illustrates the relation between the signal rectifier output voltage and the arc current in amperes D. C. and from this curve it is seen that this relationship is practically linear so that the grid voltage applied to the twin triode 77 is a substantially linear function of the arc current.

The characteristic curve of Fig. 7 shows the relationship between the regulator grid voltage and the primary voltage applied to the primary of the filament supply 52. This control curve is for the condition when the filament current limiter 81 is set for maximum current to the filament 25 and shows the range of control.

While there has been set forth in the foregoing specication a description of a preferred'embodiment of this invention, it is not desired to limit this invention to the exact details described except insofar as they may be set forth in the claims.

What is claimed is:

1. A calutron ion source regulator comprising in combination an ion source having a cathode and an anode, an alternating current supply for heating said cathode to electron emissive temperature, an alternating current rectifier power supply for supplying an arc between said cathode and said anode, a gas tube having a cathode, a control electrode and an anode, said cathode and said anode of said gas tube being connected in series with said first mentioned alternating current supply and said ion source cathode, a transformer connected in series with the alternating current input of said rectifier power supply, a rectifier connected to the output of said transformer and a phasing circuit connected between said rectifier and the control electrode of said gas tube for controlling the current through said ion source cathode inversely in accordance with the current drawn by said ion source arc to maintain said arc current substantially constant.

2. A calutron ion source regulator comprising in combination an ion source having a cathode and an anode, wall structure for defining an ionization chamber between said cathode and said anode, means for feeding material to be ionized into said ionization chamber, an alternating current supply for heating said cathode to electron emissive temperature, an alternating current rectifier power supply for supplying an arc between said cathode and said anode, a gas tube having a cathode, a control electrode and an anode, said cathode and said anode of said gas tube being connected in series with said first mentioned alternating current supply and said ion source cathode, a transformer connected in series with the alternating current input of said rectifier power supply, a rectifier connected to the output of said transformer and a phasing circuit connected between said rectifier and the control electrode of said gas tube for controlling the current through said ion source cathode inversely in accordance with the current drawn by said ion source arc to maintain said arc current substantially constant.

3. A calutron ion source regulator comprising in combination an ion source having a cathode and an anode, an alternating current supply form heating said cathode to electron emissive temperature, a source of arc current supply for maintaining an arc between said cathode and said anode, a gas tube having a cathode, a control electrode and an anode, said cathode and said anode of said gas tube being connected in series with said first mentioned alternating current supply and said ion source cathode, means connected between said source of arc current and the control electrode of said gas tube for controlling the current through said ion source cathode inversely in accordance with the current drawn by said ion source arc to maintain said arc substantially constant.

4. A calutron ion source regulator comprising in combination an ion source'having a cathode and an anode, a polyphase alternating current supply, a rectifier having the input thereof connected to said polyphase alternating current supply and the output connected between said ion source cathode and anode, a plurality of current transformers, one of said current transformers being connected y into each of said polyphase alternating current supply feeders, a single phase alternating current supply connected to said ion source cathode, rectifiers connected to the secondaries of said current transformers, a phasing circuit connected to the output of said current transformer rectifiers, a pair of gas triodes connected in series with the alternating current supply for said ion source cathode, the anode and cathode of one of said gas triodes being connected to the cathode and anode respectively of the other of said gas triodes, a pair of transformers having the primaries thereof connected in parallel across the output of said phasing network and having the secondaries thereof connected in the grid-cathode circuit of said gas triodes respectively for firing said gas triodes on alternate half cycles of the outputs of said last mentioned transformers to vary the current to said ion source cathode l1 and maintain the arc of said ion source substantially constant.

5. A calutron ion source regulator comprising in combination an ion source having a cathode and an anode, a polyphase alternating current supply, a rectifier having the input thereof connected to said polyphase alternating current supply and the output connected between said ion source cathode and anode, a single phase alternating current supply connected to said ion source cathode, a phasing circuit, rectifier means connected between said polyphase current supply and said phasing; circuit, n pair of gas triodes connected in series with the alternating current supply for said ion source cathode, the anode and cathode of one of said gas triodes being connected to the cathode and anode respectively of the other of said gas triodes, a pair ot transformers having the primaries thereof connected in parallel across the output of said phasing network and having the secondaries thereof connected in the grid-cathode circuit of said gas triodes respectively for firing said gas triodes on alternate half cycles of the outputs of said last mentioned transformers to vary the current t0 said ion source cathode and maintain the arc of said ion source substantially constant.

6` A calutron ion source regulator comprising in combination an ion source having a cathode and an anode, wall structure for defining an ionization chamber between said cathode and said anode, means for feeding material to be ionized into said ionization chamber, a polyphase alternating current supply, a rectiiier having the input thereof connected to said polyphase alternating current Supply and the output connected between said ion source cathode and anode, a single phase alternating current supply connected to said ion source cathode, a phasing circuit, rectifier means connected between said polyphase current supply and said phasing circuit, a pair of gas triodes connected in series with the alternating current supply for said ion source cathode, the anode and cathode of one of said gas triodes being connected to the cathode and anode respectively of the other of said gas triodes, a pair of transformers having the primaries thereof connected in parallel across the output of said phasing network and having the secondaries thereof connected in the grid-cathode circuit of said gas triodes respectively for tiring said gas triodes on alternate half cycles of the outputs of said last mentioned transformers to vary the current to said ion source cathode and maintain the are of said ion source substantially constant.

References Cited in the lile of this patent UNITED STATES PATENTS 1,683,194 Kearsley Sept. 4, i928 

1. A CALUTRON ION SOURCE REGULATOR COMPRISING IN COMBINATION AN ION SOURCE HAVING A CATHODE AND AN ANODE, AN ALTERNATING CURRENT SUPPLY FOR HEATING SAID CATHODE TO ELECTRON EMISSIVE TEMPERATURE, AN ALTERNATING CURRENT RECTIFIER POWER SUPPLY FOR SUPPLYING AN ARC BETWEEN SAID CATHODE AND SAID ANODE, A GAS TUBE HAVING A CATHODE, A CONTROL ELECTRODE AND AN ANODE, SAID CATHODE AND SAID ANODE OF SAID GAS TUBE BEING CONNECTED IN SERIES WITH SAID FIRST MENTIONED ALTERNATING CURRENT SUPPLY AND SAID ION SOURCE CATHODE, A TRANSFORMER CONNECTED IN SERIES WITH THE ALTERNATING CURRENT INPUT OF SAID RECTIFIER POWER SUPPLY, A RECTIFIER CONNECTED TO THE OUTPUT OF SAID TRANSFORMER AND A PHASING CIRCUIT CONNECTED BETWEEN SAID RECTIFIER AND THE CONTROL ELECTRODE OF SAID GAS TUBE FOR CONTROLLING THE CURRENT THROUGH SAID ION SOURCE CATHODE INVERSELY IN ACCORDANCE WITH THE CURRENT DRAWN BY SAID ION SOURCE ARC TO MAINTAIN SAID ARC CURRENT SUBSTANTIALLY CONSTANT. 